What is the best practices for rigging a Cartoon Character
Don't join the meshes, leave them separate.  The easiest way would be to modify the origins of your meshes so they rotate the way you want them to, instead of using armatures.

To do that, select your mesh, move the 3d cursor to the location you want your mesh to pivot from, and then select Object > Transform > origin to 3D cursor.  Now you need to parent your meshes to the body.  Select all of the appendages, and then select the body last.  Now press Ctrl + P and select object.  This will parent your arms and legs to the body.  You can now move them independently, but they will still follow the movement of the body.

If you wanted the antennas and eyes to move separately from the head, just parent the antennas to the head before you parent the head to the body.